Electric outboards for tender (budget, not Torqeedo) - your experiences please

JumbleDuck said:
That's if you go lead-acid. The Outboards Which Must Not Be Mentioned (TOWMNBM) use Li-ion batteries, which explains their insanely high prices (their batteries include GPS receivers, for some reason, which can't help). Prices are coming down, though - http://www.amazon.co.uk/LI20-12-LITHIUM-MOBILITY-ELECTRIC-VEHICLES/dp/B00SJB5XSG is a 12V, 20Ah Li-ion battery for £190 delivered. It only weighs 3kg and will give you 20 minutes of full thrust on a Minn-kota 55lb model. Still expensive, of course, but I don't think TOWMNBM are going to have the market to themselves for long
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12V 20Ah
That's 14,400 Watt-minutes.
I was on a rowing machine the other day, which gave a readout in watts. Unfortunately, I can't remember how many watts I generated.
but I think that's equivalent to a pretty hard rowing session for a middle-aged civilian?

Maybe there's a market for onboard rowing machines to recharge the batteries?
 
JumbleDuck said:
...Prices are coming down, though - http://www.amazon.co.uk/LI20-12-LITHIUM-MOBILITY-ELECTRIC-VEHICLES/dp/B00SJB5XSG is a 12V, 20Ah Li-ion battery for £190 delivered. It only weighs 3kg and will give you 20 minutes of full thrust on a Minn-kota 55lb model. Still expensive, of course, but I don't think TOWMNBM are going to have the market to themselves for long
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Looks like the battery to have, if 'a little' expensive. Am I right in saying a Li-ion battery can be used till completely flat without damaging it?

Edit: Here's a 20Ah Li-ion for £150 delivered, although it is also described as 17Ah to 22Ah for some reason.
 
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fredrussell said:
Looks like the battery to have, if 'a little' expensive. Am I right in saying a Li-ion battery can be used till completely flat without damaging it?
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Yes, just about, and they maintain a good terminal voltage till almost the bitter end. That battery works out at £10 per usable Ah which is way less than the first Mastervolt ones for boats which were, as I recall, around £25 per usable Ah. Still a long way above lead-acid (£2 per usable Ah, if that) but heading in the right direction.
 
I have an old 1.5HP "Die Hard" trolling motor I was given when we lived in the US. Never been used before I attached it to Drifter's little 2.4m inflatable tender last year. Coupled to a 32Ah gel battery. It pushes the little dink around about as fast as I could row it with 2 people aboard. I find it fine for in-harbour conditions, and the big plus is that I can lift either of the 2 separate components over my head with one hand. I did some tests on battery draw-down and I think I got about 1 hour of 75% drive before there was appreciable battery voltage drop. So, I would say that they're viable propulsion for short-ish trips but I wouldn't want to use them on a heavier dinghy or in tough conditions (including fast tide).

I don't know if the Die Hard is a salt water motor or not. The paint is starting to flake off, but it's still working (touch wood). If it does conk I think I would be tempted to get a more powerful (non-Torqeedo) version.
 
I only use my outboard if I'm going a reasonable distance as I can get out to my mooring in less than 10 mins. As I always carry oars, I prefer to use them rather than mess around with engines. It's also a bit of a trek from my parking space to my dinghy mooring over a field so that's another reason to leave the motor on the boat at all times.
 
JumbleDuck said:
Yes, just about, and they maintain a good terminal voltage till almost the bitter end. That battery works out at £10 per usable Ah which is way less than the first Mastervolt ones for boats which were, as I recall, around £25 per usable Ah. Still a long way above lead-acid (£2 per usable Ah, if that) but heading in the right direction.
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The notional Ah capacity is quoted at the 20 hour rate, I believe. What would the capacity be at the 20 minute rate?
 
pvb said:
The notional Ah capacity is quoted at the 20 hour rate, I believe. What would the capacity be at the 20 minute rate?
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Dunno, I'm afraid. my gut feeling is that Li-ion is probably less affected by discharge rate.

Tranona said:
Then why not just use oars?
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All a resolute non-user of outboards on my dinghy, this is a good question but one which I am not qualified to answer. Nevertheless, observation shows that many people prefer to use outboards for short trips by dinghy.
 
JumbleDuck said:
All a resolute non-user of outboards on my dinghy, this is a good question but one which I am not qualified to answer. Nevertheless, observation shows that many people prefer to use outboards for short trips by dinghy.
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Yes, even when I earned my living promoting and selling outboards to such people I could never understand it.
 
I paddle my Canadian canoe to my mooring, and love paddling a canoe so thats no hardship. I guess the only reason I want an outboard is for using the inflatable in windy conditions (canoe usually left tied to mooring). Rowing a flubber with the wind up is bit of a chore - they skit around all over the show in my limited experience.

Incidentally, I recently paddled my canoe next to my pal that was rowing a small fibreglass tender - you would be amazed at how slow rowing is compared to paddling. My mate's a good rower, and yet I found myself paddling at less than half the speed I normally would to keep to his pace. I'm always surprised how few canoes are used as tenders. I can get two adults and gear in my canoe. It weighs 23kg, and sails well (takes an oppie rig).
 
Tranona said:
Think most people would consider a 100 yard range twice a day pretty limiting.

Of course these motors will move a dinghy slowly over short distances, but they are only a substitute for an outboard over a very limited range of capabilities. If you accept the limitations that's fine for you, but would suspect most people want more.
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If I was limited to 100yards then I to would find this pretty limiting.

I use mine for getting to the boat, and messing around sometimes I row, sometimes I motor, sometimes I row and motor.

I get a lot more than 100 yards, I can mess around all day.
 
Perhaps all the discussion can be summarised in this way...
A Torqeedo or small Trolling motor will push a tender along.
The difference perhaps is that a Torqeedo is a substitute for a small petrol outboard motor whereas the Trolling motors are a substitute for a pair of oars.
 
foeu said:
Perhaps all the discussion can be summarised in this way...
A Torqeedo or small Trolling motor will push a tender along.
The difference perhaps is that a Torqeedo is a substitute for a small petrol outboard motor whereas the Trolling motors are a substitute for a pair of oars.
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Sod the lot of them, I want a sailing tender! :-)

I went to a talk by a couple who'd sailed a lot of Polynesia, they seriously reckoned a sailing tender was a godsend. No fuel to buy, no worries etc.
The time a tender is not nice to row tends to be when there's breeze to sail?
 
lw395 said:
Sod the lot of them, I want a sailing tender! :-)

I went to a talk by a couple who'd sailed a lot of Polynesia, they seriously reckoned a sailing tender was a godsend. No fuel to buy, no worries etc.
The time a tender is not nice to row tends to be when there's breeze to sail?
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As I said upthread, we use a sailing tender. There wasn't much good sailing for it this summer, but it's great fun when the wind's right, and when the wind's wrong there are oars.
 
foeu said:
You can charge the Torqeedo battery directly from the ships battery, no need for an inverter. They sell a lead or make one, cigar plug direct to Torqeedo.
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I know and have one, but (at the expense of power loss) an inverter with fast charger plugged in is very much faster to charge. I haven't tried to find to find out why.
 
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